1. Field of the Invention
This invention relates to the field of rotary power carving tools, and in particular, to a safety shield for a rotary power carving tool.
2. Background Art
When using hand held power tools to carve or grind materials, such as wood, toxic material and flying particles of carbide bur may be produced. These particulate materials may be breathed into the lungs of the user or deposited onto the skin of the user, causing irritation and possible health hazards. Additionally, these particulate materials may adhere to the tool and clog the tip. Therefore dust masks, long-sleeves, hats, aprons, gloves and goggles are often required when using these devices in order to protect the user and frequent interruptions in the use of the tool are often required for cleaning and maintenance in order to protect the tool.
Thus it is advantageous to remove the particulate materials produced by power tools in order to prevent them from being deposited on the user or on the tool. It is known in the art to provide dust boxes which include exhaust filters for this purpose. However, these dust boxes do not eliminate all the particulate materials and they clog quickly. Because of the tendency to clog quickly they require constant emptying when these power tools are operated. Additionally, the usefulness of these devices is limited because they are not portable.
It is also known in the art to provide portable safety shields which may be directly attached to hand held power tools to help protect users from particulate materials. Additionally, it is known to provide a combination safety shield and particulate collection attachment. These devices permit more convenient use of power hand tools in locations where it is not possible to use dust boxes.
For example, U.S. Pat. No. 3,256,648, issued to Subonovich, discloses such a shield and particulate collection attachment. The particulate collection attachment of Subonovich has an opening from which an upwardly extending hollow sphere is mounted for movement within a socket. The socket is adapted to mate with a motor for driving a sanding disk. The particulate collecting attachment taught by Subonovich is also provided with an opening extending into a fitting which terminates a circular pipe section. The pipe section is adapted to be connected to a vacuum hose in order to remove the particulate materials created by use of the power tool. Thus the device taught by Subonovich is adapted to remove particulate materials by means of a vacuum.
U.S. Pat. No. 4,124,956, issued to Levinson, discloses a portable rotary bur which is releasably secured within a vacuum shroud. A vacuum tube is coupled to the vacuum shroud for removing particulate materials. However the vacuum shroud of Levinson is formed with a flared mouth portion which does not extend to the cutting bur end. Therefore as particulate materials are created at the bur end and accelerated, a substantial portion may be propelled away from the shroud because no vacuum is applied to them.
In order to solve this problem, the source may be applied at the actual point of work. For example, U.S. Pat. No. 4,245,437, issued to Marton, discloses a spring loaded telescoping tubular vacuum housing for a hand held power tool. When the vacuum housing is connected to a vacuum source the device taught by Marton is adapted to remove loose material created by grinding. As a grinding bit sinks deeper into a work piece the telescoping portion retracts. Thus a vacuum seal is preserved. However, the device taught by Marton is not effective for tools which must be operated at varying angles with respect to the workpiece, for example, with wood carving.
When using portable vacuum shield devices for hand held power tools a vacuum hose may be used to apply a vacuum, from a suitable vacuum source, to the vacuum shield. It is often necessary to couple the vacuum hose to vacuum sources having differing size mating openings for receiving the hose. Thus it is useful to have a single mating device for coupling the hose to any one of a large number of mating openings. A device for this purpose is taught in U.S. Pat. No. 4,997,209, issued to McGrath. McGrath discloses a hollow tapered sleeve that is provided with a series of different sized and tapered portions of varying lengths and angles which enable the sleeve to be used with a variety of inlet valves. Additionally, U.S. Pat. No. 4,101,149, issued to Fleischer teaches a coupling device which may be used to couple vacuum hoses to vacuum sources of varying sizes.